Nitrourea product



Patented May 22, 1945 UNITED "STATES PATENT OFFICE 2,376,474 A NITROUREA PRODUCT Lawton Arthur Burrows, Walter Cornelius Holmes, and Charles Philip Spaeth, Woodbury, N. J., assignors to E. I. du Pont de Nemours &

I Delaware Company, Wilmington, Del., a corporation of No Drawing. Application October 29, 1942,

Serial No. 463,856

4 Claims. (01. 260-553) This invention relates to an improved nitrourea product, and, more particularly, to a method of bringing about said improvement.

Nitrourea possesses considerable importance asan organic intermediate. As prepared by the methods of the prior vart,- the product shows a tendency to decompose at slightly elevated temperatures, particularly in-the presence of water. 1

A greater degree of stability would be desirable and would simplify and add safety during its storage, transportation, and use.

An object ofthe present invention is a nitrourea product possessing improved keeping properties.

A further object is such a product having an enhanced degree of stability at elevated temperatures and in the presence of water. A still further object is a method of treatin nitrourea whereby the foregoing improved product is obtained. Additional objects will be disclosed as the invention is described more at length hereinafter.

We have found that the foregoing objects are attained, and the disadvantages of the prior art overcome, when we mix nitrourea with airela-j tively small amount of a non-volatile acid, or with the acid salts of such acid, that is to say salts in which only a part of the replaceable hy- The stabilizing'efiect of 1% H2804 parent in the above.

Example 2 :A sample of nitrourea was treated with a small amount of aqueous sulfuric acidso that the sulfuric acid content was 0.53% and water 4.24%. This sample wasistored at a" temperature of 90- 100 F. for an extended period, a control sample of untreated nitrourea being maintained uni der exactlythe same conditions. An initially is very apwet sample was used because this was believed to constitute a. severer test. At definite time intervals, the respective samples were tested for water content and for loss in weight in two hours at 70 C. These results are indicative of stability, since" water content appears to increase and to promote instability, and a sample that shows a relatively low weight loss after two hours drogen has been displaced by the base. We find sulfuric acid,sulfamic acid, and other acids in solid form to function satisfactorilyin accordance with the invention and impart a markedly increased stability to nitrourea. Likewise, the

acid salts of such acids have a favorable 'stabilizing effect, particularly ammoniumacid sulfate.

The following examples will serve as specific illustrations of the beneficial results obtained by the inclusion with nitrourea of certain acids and acid salts: f Example 1 Preliminary tests with relatively unstable samples of nitroureawere carried out, two samples at C. is considered satisfactory. The following results were obtained:

Time, days Sample A:

No stabilizer. Per cent HIO-- Per cent loss at 70 0 mple B:

0.53% H1804"-.- Per cent 1120.. Per cent loss at 70 C Decomposed. Test discontinued.

The foregoing results show that the presence of a small amount of sulfuric acid adds greatly to beingtested, with and without the addition of 1 sulfuric acid, for the amount of gas evolved on heating at 49 C. for two hours. The following results were obtained:

Sample 1: l a Gas evolution, cc. No stabilizer. 10.2 1% H250 5.8 Sample 2:.

No stabilizer j 5.2 I H 1%H SO the stability on storage of nitrourea at elevated summer temperatures, even in the presence of high moisture content.

While sulfuric acid possesses marked sta bilizing properties toward nitrourea, as shown in the foregoing, it has the disadvantage of being a corrosive liquid. A solid material that would have the ability to accept ammonia would be more desirable in this respect. In the following example, tests were carried out using such materials.

Example 3 .The following results were obtained in the manner described in Example 1. v

Stabilizer Sample Per cent H2O Per cent loss at 70 0.

Sample D I Per cent H2O Per cent loss at 70 0.

Sample E Per cent H2O Per cent loss at 70 0.

Sample F Per cent H2O Per cent loss at 70 C Sample G Per cent H2O .4. Per cent loss at 70 0.

Sample H Per cent H1O Per cent loss at 70 0.

The-presence of the'ab'ove solid acids and acid salts is seen to have been beneficial.

Example 4 An additional series of tests was carried out by substantially the same procedure,- in which subfami'c'acid was blended with the'nitrourea, The

tests: are shown; just prior: to the appearance of serious decomposition" whereas,- as lorigasth'e' sta bilizer is effective. the moisture content remains substantially constantcor decreases. L

The stabilizer may be introduced into'the prod uct in any desired manner. Stabilizers of the solid type in finelydi-vided form maybeblefided following results were obtained: directly in the desired amountwith the nitrourea.

Time, days Sample J;

No stabilizer Per cent H2O 2.72 D Per cent loss at 70 C. 0. 21 Sample-K: 1 1

0.95% sull'amic acid Per cent H2O 2. 54 2. 69 2.00 D 7 Per cen't'loss at 70 C. 0217 r 0.00 0.41 Sample L: g v

No stabilizer Per cent H10 016 0173 1. 4.94 Per cent loss at 0.16 2.31 7.99 85 Sample M:

0.95% sulfamic acid I Per cent Hl0..- o.42 0 37 0,31 0 29 0.39 0.47 0. 53 0.55 Per cent loss at 70"0- 0. 09 0.01 0.06 0.19 0.10 0.21 0.19 1 0. 17

" 1 Test still'iii progress.

The samples containing sulfamic acid will be seen. to be considerably more stable on storage than those containing no stabilizing material. Sample M, for example, showed no signof deterioration at the end of 98' days of storage;

As shown in. the foregoing, nitrourea tends to decompose on storage and to evolve gaseous prodonstrated that, in the first phases of decomposition, the ammonia'combines with undecomposed nitrourea' to: form the ammonium salt of nitrourea. The latter has been found to possess lower stability thannitrourea, particularly in the presence of water and at slightly elevated temperatures. The evolvedammonia however, will preferentially react with acidsand acidsalts such 'asare disclosed herein, therebypreventing the ucts, one of which is ammonia. It has been dem- Likewise, any of the acids may be introduced in aqueous solution or dissolved in; any solvent trithe desired strength. If the nitrourea is mixed with inert sol-ids, 'suchsol-ids may desirably be treated with the acid or acid: salt prior to'blending with nitrourea.

-We' have stated that our invention comprises the blend-ing of nonvolatile"acidsand their acld salts with nitrourea; and thereby promotlng tlie stability By the term norrvolatileacid's we ii'i' tend to designate acids having a boillngpolnt above C., for examplefsu'lfuric, propionic and acetic acids. Preferably, however, we employ solid acidic materials foreilaemples e1 1 sulfarni'cacids; oxalic cid, acidbenz fie tartar sulfdn'ic a cid} and: pho'sp "em-atlas, and acidsalts asainmo'niiim d'suIfate-an acidsulfatei Our preferred 'compdund for use are sulfamic acid, oxalic a'ci clfan iifiofiii'ifit-alcld sulfate; ahdsodium acid sulfate. vj

Relatively small amounts'of tne'st'a f like sumcient'to give the desired effect. Weffind a range of amounts between 0.05% a d 0? satisfactory. "Actually,fa'safe pr p to be to" empiey such an'afiio'imtbfstabi l'z'ef that tote the equivalent of $40 mol of replaceable hydrogen will be present for each 100 grams of nitrourea.

We have described our invention at length in the foregoing. It will be understood, however, that many variations in details of procedure and compositions may be introduced, without departure from the spirit of the invention. We intend to be limited, therefore, only by the following patent claims.

We claim: t

1. A stabilized product comprising nitrourea and a solid compound taken from the group consisting of acids and acid salts.

2. A product comprising nitrourea and sulfamic acid in an amount between 0.05% and 4.0% of the weight of the nitrourea.

3. A product comprising nitrourea and ammonium acid sulfate in an amount between 0.05% and 4.0% of the weight of the nitrourea.

4. A product comprising nitrourea and oxalic acid in an amount between 0.05% and 4.0% of the weight of the nitrourea.

LAWTON ARTHUR BURROWS. WALTER CORNELIUS HOLMES. CHARLES PHILIP SPAETH. 

